The invention relates to a clamping pin for use in an external fixation system for adjustment of a bone fracture.
The prior art teaches several locking mechanism or clamping elements to connect a cylindrical element with a frame of an external fixation system via an opening that is arranged within the frame. Such frames can have different shapes, for example the shape of a circle, a segment of a circle, rectangular etc. and enclose a limb of human body at least partly.
U.S. Pat. No. 5,681,309 discloses a distraction apparatus comprising two rings to which pins are attachable. The pins provide a connection between bony structure and the rings of the external fixator. The two rings are connected by means of several rods. The length of the rods is adjustable in order to adjust the position of the two rings relative to each other. Each ring comprises a plurality of openings into which the rods can be introduced. The rods are fixed to the ring by means of a locking mechanism comprising a nut and a bolt. In order to connect the rod with the ring two nuts (one on each side of the ring) are used and tightened against each other. The assembly comprises further a functional element such as a holder of a pin that is connected to a bone fragment.
The handling of bolts and nuts is cumbersome for the medical practitioner as a tool has to be used on both sides of the ring. Additionally the medical practitioner has to handle two elements, namely the bolt and the nut. Due to that it may be likely that some of the elements may fall down. Furthermore the accurate positioning is also rather troublesome as the position of the ring usually shifts slightly when the nuts will be tightened securely.
A pin holder is shown in U.S. Pat. No. 6,342,054 and in U.S. patent application Ser. No. 12/288,332 having the same filing date as this application and listing Christian Steiner, Meinrad Fiechter, Beat Knuchel and Vinzenz Burgherr as inventors.